[time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

Magnus Danielson magnus at rubidium.dyndns.org
Wed Jan 19 19:55:11 UTC 2011

On 01/19/2011 06:44 PM, Poul-Henning Kamp wrote:
> In message<DBB70463B9D04F6589FBF97B2E4BE131 at vectron.com>, "Bob Camp" writes:
>> Conventional gas cells have a finite lifetime on the
>> lamp.
> It used to be that Rb's would fail lock because the bulb dimmed from Rb
> absorption into the glass, but I think they got that fixed with a teflon
> coating.
> Thes days most of them ultimately fail from the high operating temperature,
> through a variety of mechanisms.
> For the CSAC, my bet would be that the laser is the limiting factor.

I agree, for the CSAC I would expect that the laser would slowly dim, 
especially as it sits within the oven. Not optimum to keep the junction 
temperature down.

For my older Rubidium, the Rubidium lamp had splattered the Rubidium. 
When I heated it the first time I did get a dimmed glass, but heating it 
again orienting it properly (so hot gas rising into the back where I 
wanted it) I resolved the problem... within minutes. So I really wonder 
if it absorbs into the glass.

Exactly why splattered rubidium cause a problem for the rubidium lamp I 
am not 100% sure about, but my guess is that maybe it will expose too 
large area and thus causing too large gas-pressure to let the RF-field 
light up the gas. If someone who actually know could explain it, I would 
be happy to learn.


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